1. Field of the Invention
The present invention relates to a disk brake                with a brake disk having a preferred rotational direction;        with a first brake pad with a first center of gravity on a first side of the brake disk;        with a second brake pad with a second center of gravity on a second side of the brake disk; and        with a caliper for transmitting the braking forces generated by the second brake pad to the first side of the brake disk.        
2. Description of the Related Art
In general, the design and operation of disk brakes differ depending on the way the clamping device is installed in the brake caliper. FIGS. 1-4 show examples, namely:                FIG. 1 shows a schematic cross-sectional view of a sliding caliper disk brake with one-sided clamping according to the reactive-force principle;        FIG. 2 shows a schematic cross-sectional view of a fixed caliper disk brake with one-sided clamping according to the reactive-force principle with a floating brake disk;        FIG. 3 shows a schematic cross-sectional view of a fixed caliper disk brake with a two-sided clamping device and a fixed brake disk; and        FIG. 4 shows a schematic plan view in partial cross section of a disk brake.        
When the problem is described in the following on the basis of a sliding caliper disk brake, all of the explanations will also apply in an analogous sense to caliper disk brakes of the hinged caliper or fixed caliper type with one-sided or two-sided clamping in which a brake pad is held, guided, and/or supported directly on the free, that is, on the unsupported, sidepiece of the caliper. This “free sidepiece” is the sidepiece which absorbs the circumferential braking forces on this side and transmits them to the other side of the caliper via the bridge part, which spans the brake disk. The sidepiece on the other side of the brake caliper is the sidepiece that is connected to a stationary part. That is, the invention is not limited only to sliding caliper disk brakes.
According to the state of the art illustrated schematically in FIGS. 1-4, the disk brake has a brake caliper 1, the two sidepieces of which extend around a brake disk 4. The caliper is also equipped with at least one clamping device 5 mounted on one side of the brake disk to press the brake pads 2, 3 against the brake disk 4, one of these pads being supported and guided in each sidepiece of the brake caliper, one on each side of the brake disk. The brake pads 2, 3 are held/guided so that they are opposite each other and so that their axes of gravity or centers of gravity S1, S2 (FIG. 4) lie on top of each other when they are displaced toward the brake disk and meet the plane of the brake disk at a right angle.
In this case, the brake caliper 1 is connected on one side of the brake disk 4 by means of a fixed part 6 to a vehicle part 7 (not shown), which is referred to as the “axle part”. By way of the fixed part 6, the braking torques absorbed by the brake caliper 1 when the brake is actuated are transmitted to the vehicle part 7 (axle part). Especially when a separate guide and support part such as a brake bracket, which absorbs the circumferential braking forces, is not provided for the brake pad 3 on the side closer to the wheel rim, when, on the contrary, this brake pad is attached directly to the free, unsupported sidepiece of the brake caliper, the brake caliper 1 has a pronounced tendency, when the brake is actuated, to tilt toward the trailing side of the brake disk, i.e., the side which trails when the brake disk 4 is rotating in rotational direction D.
As a result, the rim-side brake pad 3 is subjected to disadvantageous tapered wear as a result of nonuniform pressure on the facing, but in addition, the guide or support parts are also subjected to extreme loads; exactly which parts are subjected to these loads depends on the design of the caliper of the disk brake. In the case of a sliding caliper or hinged caliper, these parts are the pin guides 8 or bearing pins, whereas, in the case of a fixed caliper, the part in question is the mounting flange. The devices that guide or support the brake caliper on the stationary vehicle part must therefore be designed to have sufficient strength.
Disk brakes, especially the disk brakes used in commercial vehicles, are required to absorb very high braking torques when being used to decelerate a vehicle. The dimensions of the parts must therefore be suitably large. Nevertheless, even this does not always make it possible to prevent the caliper from tilting.
In the disk brake according to DE 197 43 538, therefore, in which the brake pad is attached directly to the free sidepiece of the caliper (on the rim side), the attempt is made in the case of a sliding caliper to prevent the caliper from tilting by providing the brake bracket with lateral guide arms, which extend across the brake disk to serve as a support/contact surface for the brake caliper, as a result of which it is said that the caliper can be prevented from tilting. Nevertheless, because of the narrow guide tolerances, undesirable frictional torques are caused by contact with the caliper during the braking and releasing operations, and these torques interfere with the sliding function of the caliper. The high bending and friction torques on/in the guide bearings of the sliding caliper are also disadvantageous.
Another possible way of solving the problem is described in European Patent No. 709 592, according to which the guide for the brake pad on the clamping side is again provided in the fixed part of the brake, and the brake pad on the rim side is provided on the caliper sidepiece. In this case, guide pins guide the caliper.
In both of the solutions according to the state of the art described above, the centers of gravity of the brake pads are opposite each other with respect to the brake disk. The brake pads are therefore symmetric to each other.
Because the brake according to European Patent No. 709 592 uses an almost plate-shaped brake bracket, it would be a good choice for commercial trucks simply because of its reduced weight, but disk brakes with this design, even small disk brakes and disk brakes used in passenger vehicles, suffer from enormous disadvantages, which are expressed primarily in the tendency of the brake caliper to tilt. The results of such tilting are high bending torques and friction torques (the torques which oppose the tilting of the caliper) in the caliper guides and uneven contact between the facing on the rim side and the disk, which results in disadvantageous tangential wear.